Battery electrode substrates and method of making same

ABSTRACT

A three-dimensional substrate material for use in constructing battery electrodes comprises a sintered matrix material selected from the group consisting of reticulated metal foams, conductive fibers and metal powder compacts, and a porous covering layer of a polymeric mesh material, flexible metal screen or metal fibers, bonded to at least one surface of the matrix material to retain the sintered matrix material substantially within the planar surface of the surface of matrix material during spiral-wounding of the chemically loaded matrix material.

This is a continuation of application Ser. No. 07/979,830 of Nov. 20,1992 now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to improved three-dimensional batteryelectrode substrate materials and, more specifically, to a nickelelectrode substrate which provides enhanced active substrate filling andretention within the electrode matrix and which permits enhancedmechanical strength and integrity during cell construction and reducedshorting between electrode layers in the cell after fabrication, thusenhancing cell manufacturing yield.

At present, rechargeable battery electrode substrates are manufacturedfrom a wide variety of reticulated metal foams or sponge-type metalmaterials, metal fibers and metal powder compacts. Specifically, nickelthree-dimensional battery electrodes (metal fibers) are made primarilythrough a sintering process utilizing a felt-type conductive porousmaterial composed of nickel fibers and nickel powder, such, as carbonylnickel powder. The resultant nickel battery electrodes generally containbetween 75-90 weight percent nickel fiber and 10-25 weight percentnickel powder. An example of such a battery electrode is described inJapanese Patent Publication 63-12473. This publication discloses afelt-type nickel battery electrode containing long nickel fibers andnickel powder. In such an electrode, the fiber and powder provide aporous material having cavities or voids therein which on average areapproximately 60 microns in diameter. After sintering of the fiber andpowder porous material, the active chemicals such as, nickel and cadmiumhydroxides are added or loaded into the porous material to generate theelectrical energy of the battery electrode by chemical reaction. Theactive chemicals are loaded or added to the fiber substrate or matrix bya number of techniques, including chemical or electrochemical conversionand mechanical injection of high viscosity aqueous pastes of the activematerials or chemicals.

As the demand for higher capacity electrodes has increased, the priorart three-dimensional battery materials or substrates and, inparticular, the prior art porous matrices or structures comprisingsintered long nickel fibers and nickel powders have been found to beonly partially effective in that the nickel powder contained within thefibrous substrate tends to block the entry of active chemicals into thepossible loading areas within the fiber matrix. Accordingly, thereticulated metal foams, metal fiber and powder compacts, in accordancewith the prior art, appear to exhibit a porosity of a level whichrestricts the penetration of the active chemical or chemicals to thecenter of the matrix, and which limits the amount of active chemicalsthat may be loaded into the matrix, thus resulting in reduced electrodeefficiency.

A further disadvantage of such prior art three-dimensional electrodesubstrate structures is that the metal fiber matrix is composed of fiberlengths exceeding about a quarter and a half inch in length. It isbelieved that this length of long fiber was desirable to facilitatedistribution of the active chemical space throughout the fiber matrix toprovide an overall fiber matrix containing a predetermined weight offiber material. Also, it has been found that the subsequent processingof such metal fiber matrices, metal foams and metal powdered compactsand layering of the electrode material results in an electrode materialwhich possesses inadequate tensile strength and ductility, whichsubstantially reduces the production yield of material which may bespiral-wound into cells for insertion into the completed electrodeassembly.

Additionally, such prior art three-dimensional spiral-wound electrodematerials possess substantial fiber ends rising from the spiral-woundsurface or surfaces of the completed electrode assembly, a problem whichresults in a brittleness in bending which substantially increases theamount of breaking during processing of the electrode. Furthermore, theloose fiber ends and broken fibers extending from the surface of thespiral-wound electrode, which ends often times penetrate the separatormaterial thereby resulting in a shorting out between electrodes of thefinished battery assembly.

SUMMARY OF THE INVENTION

It is one object of the present invention to provide an improvedthree-dimensional electrode substrate possessing substantially improvedloading and retention of the electrode active material.

It is still another object of the present invention to provide animproved three-dimensional battery electrode substrate possessingincreased surface area, pliability, ductility, flexibility and tensilestrength to provide nominal electrode substrate material particularlyuseful in cell construction.

Still another object of the present invention is to provide an improvedbattery electrode substrate which possesses superior mechanical strengthand integrity and having a surface resistance to mechanical breakage anddamage during cell construction and use.

Another object of the present invention is to provide an improved highcapacity battery electrode substrate having a synthetic material adheredto the surface of the electrode substrate which provides enhanced activechemical substrate material filling and retention within the electrodematrix or substrate.

Still another object of the present invention is to provide an improvedloaded battery electrode having a surface condition conducive to theutilization of reduced separator thickness thereby enabling batterydesigns that maximize cell capacity.

It is still another object of the present invention to provide animproved three-dimensional electrode substrate having a porous coveringlayer or means bonded and in intimate physical contact with theelectrode substrate to permit chemically loading of the active materialinto the substrate and to prevent mechanical breakage and damage duringspiral-winding and cell construction by retaining the metal foam ormetal fibers within the electrode substrate from substantiallypenetrating the plane or surface of the electrode substrates.

It is yet another object of the present invention to provide anincreased yield of useful electrode material when such material isspiral-wound to complete the electrode assembly.

It is still a further object of the present invention to provideimproved methods of manufacturing the battery electrode substratematerials possessing enhanced loading and retention characteristics ofthe active chemical substrate material within the substrate.

In accordance with the present invention, a three-dimensional electrodesubstrate or matrix material, such as, a nickel prior art batteryelectrode, provides a conducting, porous nickel fiber matrix whichaccepts the active chemical materials which are loaded within the voidareas of the fiber matrix. These prior art long nickel fiber matricesare comprised of nickel fibers that extended one quarter to one halfinch in length, with the long nickel fibers preferably comprisingbetween 70-90% of the total weight percent of material in the nickelbattery electrode.

It has been found that by applying a synthetic or polymeric meshmaterial or resinous coating or web, or porous resinous fiber onto thenickel fiber-nickel powder matrix, made in accordance with the priorart, a more porous electrode structure is formed which possessesincreased active chemical material loading and retention. The directapplication of the synthetic mesh, porous resinous coating, or porousresinous fibers onto the sintered prior art nickel fiber-nickel powdersubstrate material may be accomplished in a number of ways includingapplying a synthetic mesh material by pressing the material in heatedcontact with the nickel electrode matrix structure. The synthetic meshor web fabric is a resinous fabric which is preferably selected toprovide a porous chemically resistant surface which is compatible withthe electrolyte system used in the completed electrode battery. Theporous resin coating may be applied to the electrode substrate materialby utilizing a hot melt spray, an aqueous slurry, conventional air andwet layering, fluidized bed, electrostatics, steam calendering of apreformed fabric, and a hot calender lamination of the preformed fabric.The resin fabric, web, or coating may be bonded to one or both surfacesof the metallic substrate matrix used as the electrode or carrier forthe active materials in the electrochemical cell.

In still another embodiment of the present invention, a layer of finediameter metallic fibers may be bonded to one or more of the outersurfaces of the prior art three-dimensional battery electrodesubstrates. After the direct application of the multi-layered finefibers to the three-dimensional electrode substrate, the resultantlayered substrate is sintered, then calendered and sintered again priorto loading with the chemically active material by the electrode cellmanufacturer. The addition of the surface network of layers of finediameter fibers provides a lattice of increased surface area andprovides a sinter-bonded surface layer to the underlying electrodesubstrate. The small diameter surface fiber layer may be applied to thesurface of the three-dimensional battery substrate by conventional airand wet layering, aqueous spray and roll coating techniques, techniquesknown in the art. The resultant multi-layered battery electrodesubstrate provides an electrode structure which possesses increasedloading and retention of the electrode active material. Additionally,the enhanced electrode substrate, coated with multiple layers of finediameter fibers, provides a substrate surface effect which substantiallyreduces battery cell shorting and provides extended rechargeable batterycell life cycling performance by substantially reducing the number ofmetallic fiber ends extending from the surface of the electrode afterthe electrode is chemically loaded and then rolled or spirally-wound tocomplete the electrode cell assembly.

In still a further embodiment of the present invention a flexible finemesh metal screen may be bonded to at least one surface of the longnickel fiber-nickel powder substrate to substantially reduce the numberof metallic nickel fiber ends extending from the planar surface of theelectrode after the electrode is chemically loaded and then rolled orspirally-wound to complete the electrode cell assembly.

The term three-dimensional battery electrode substrate generally refersto an electrode having a more extensive electrochemical structure oractivity in a dimension normal to the electrodes frontal surface thandoes a planar electrode. Such sintered three-dimensional batteryelectrodes substrates are, preferably, a conductive fiber or metal fibermatrix material. However, it is within the scope of the presentinvention that the sintered metal matrix material may be reticulatedmetal foams or metal powder compacts.

The matrix of planar state-of-the-art electrodes, being constructed frommetallic screen or mesh composed of wrought wire or filaments, isgenerally quite ductile and capable of being rolled or bent into a smalldiameter spiral cylinder without breakage of the filamentary elements ofthe matrix. The matrix of three-dimensional electrode structuresgenerally are constructed from non-wrought metallic filaments from asintering or electrodeposit type of process. Such electrode structurestend to be relatively less ductile in rolling or bending into a smalldiameter spiral cylinder and tend to exhibit a degree of brittlenesswith breakage of some matrix elements upon bending. These less ductileelements of the three-dimensional electrode matrix are the primary causeof shorting when they protrude from the surface of the completedelectrode cell.

It is also within the scope of the prevent invention that the porouscovering layer bonded to at least one surface of the three-dimensionalelectrode provides a loaded cell electrode structure that possessesincreased conductivity and lowered resistivity over non-coatedthree-dimensional electrodes. This permits the electrode material of thepresent invention to be used in spiral-wound electrode cells as well asbe used in planar or plaque cells which may be stacked in the completedcell assembly. Although such planar or button cells may be configured orstacked in a final cell assembly as a non-planar arc, in this sense,they are considered substantially planar for purposes of thisdisclosure.

In the present invention it is preferred that the porous covering layerbe applied and bonded to both the upper and lower surfaces of thethree-dimensional electrode to provide a laminate or sandwich structure.Accordingly, it is within the scope of the present invention that theproper orientation and handling of the spiral-wound chemically loadedmatrix material will require that only the outside peripheral surface ofthe wound cell requires a bonded porous covering layer to substantiallyreduce the number of conductive or metallic fiber ends extending fromthe peripheral or planar surface of the complete electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing description and other characteristics, objects, featuresand advantages of the present invention will become more apparent uponconsideration of the following detailed description, having reference tothe accompany drawings, wherein:

FIG. 1 is a schematic view showing the steps of manufacturing a nickelbattery matrix or substrate in accordance with the prior art;

FIG. 2 is the schematic view showing the steps of manufacturing thesynthetic mesh bonded to the nickel battery matrix or substrate inaccordance with one embodiment of the present invention;

FIG. 3 is an enlarged schematic top plan view of the synthetic meshbonded to the nickel battery substrate manufactured in accordance withFIG. 2;

FIG. 4 is a sectional view taken along lines 4--4 in FIG. 3;

FIG. 5 is a schematic view showing the steps of manufacturing multiplelayers of fine diameter fibers bonded to a surface of a nickel batterysubstrate in accordance with a further embodiment of the presentinvention;

FIG. 6 is an enlarged schematic top plan view of multiple layers of finediameter fibers bonded to a surface of a nickel battery substratemanufactured in accordance with FIG. 5;

FIG. 7 is a sectional view taken along lines 7--7 in FIG. 6;

FIG. 8 is an enlarged schematic top plan view of the wire screen bondedto at least one surface of a nickel battery substrate in accordance witha further embodiment of the present invention; and

FIG. 9 is a sectional view taken along lines 9--9 in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein like numerals have been usedthroughout the several views to designate the same or similar parts; afibrous nickel battery matrix, substrate or material 10 has beenmanufactured using conventional apparatus and techniques, as is known inthe art. In the past, such nickel-fiber matrix materials have beenutilized as the fiber matrix material for use in preparing nickelbattery electrodes when the matrix material is calendered and pressed tosize to receive nickel powder as a paste or filler material toimpregnate the fiber matrices with the nickel powder.

In accordance with such prior art teachings, the prior art techniqueshave utilized between 70-90 percent by weight nickel fiber material and30-10 percent by weight nickel powder as the paste or filler material toprovide a conventional fiber matrix or substrate material that issintered in a reducing atmosphere. A preferred material containing 80percent by weight long nickel fiber and 20 percent by weight nickelpowder, normally provides, for example, an end weight of 0.45 grams persquare inch. This material results when the fiber matrix of 0.36 gramsper square inch would be coated with 0.09 grams per square inch ofnickel powder, as is known in the art. The nickel fibers are long fibershaving a length in excess of 0.25 inch to 0.5 inch in length, with thenickel fibers having a nominal 25 micron diameter.

Referring now to FIG. 1, there is shown a schematic view illustratingthe steps of manufacturing a nickel fiber-nickel powder matrix orsubstrate 10 in accordance with the prior art. Long nickel fibrousmaterial 12 is introduced into a calendering apparatus 13 and pressed toreceive the filler material, nickel powder and/or nickel oxide powder14, which is applied by a roller coating apparatus 15, including hopper16 and rollers 17. The filler material 14 is deposited onto thecalendered and pressed fibrous material and rolled by rollers 17 to auniformed thickness, pressing the filler material 14 into the fibermatrix to impregnate the fibrous matrix with the filler material. Thenickel battery matrix or substrate 10 thus formed is then passed througha sintering oven 18 and then wound on a take up reel 19, for example,for storage prior to its use and the manufacture of the batteryelectrodes substrate in accordance with the present invention.

In accordance with the present invention, a synthetic or polymeric meshmaterial or porous covering layer means 20 may be bonded to at least oneof the surfaces of the nickel fiber-nickel powder matrix 10 to provide aporous electrode structure which possesses increased active chemicalmaterial loading and retention as well as providing a substantialreduction in the number of metallic fiber ends which extend from thesurface of the electrode after the electrode is chemically loaded andthen rolled or spirally-wound to complete the cell assembly. A suitablepolymeric or nylon mesh material useful in practicing the presentinvention may be a polyester, polyolefin, polyamide, or other syntheticmaterial. One commercial material useful in the present invention ismarketed under the trademark SHARNET™ which is an adhesive webmanufactured and sold by Applied Extrusion Technology, Inc.

FIG. 2 illustrates the process for applying a resinous or polymericcoating onto the surfaces of a sintered nickel fiber-nickel powdersubstrate material. As shown in FIG. 2, the sintered wound nickelfiber-nickel powder substrate 10 is wound on a take up reel 19 which ismounted on a let off stand 21 for feeding into a laminator station 22.The laminator station 22 is comprised of an upper polymeric coated beltapparatus 23 and a lower polymeric belt apparatus 24 which guides thesintered nickel fiber-nickel powder substrate 10 between heated pressurerollers 25 to bond the resin or polymeric web or mesh material 20 ontothe nickel fiber-nickel powder substrate 10, as will hereinafter bedescribed.

Preferably, the polymeric or synthetic mesh or web material 20 isapplied to both surfaces of the nickel fiber-nickel powder substrate 10.Accordingly, reels containing the resin netting, mesh or web 20 aremounted on the let off stand 21 to facilitate feeding of the resinnetting or mesh 20 onto the upper and lower surfaces of the substrate10. Preferably, it is desired to utilize a release liner 29 between themesh material 20 and the lower teflon coated belt 24 and heated pressurerollers 25 as well as utilizing a release liner 29 positioned betweenthe mesh material 20 and the upper teflon belt 23 and the heatedpressure rollers 25 to prevent accumulation of the polymeric materialonto the heated pressure rollers and belt.

The resultant polymeric coated nickel fiber-nickel powder substratematerial 28 is schematically shown in FIG. 3. In such a view, the outercovering or surface of the polymeric coated nickel fiber-nickel powdersubstrate includes a polymeric or mesh material 20 on the outer surfaceof the substrate 10 with the inner portion of the substrate beingcomprised of long nickel fibers 12 and nickel powder 14. The polymericor mesh material 20 when heated and applied to the bonded surface of thesubstrate 10 yields a non-uniform open spaced covering that permits thebattery manufacturer to load the polymeric coated nickel fiber-nickelpowder substrate with the active chemical materials for completing theassembly of a cell. Additionally, it has been found that the nickelfiber-nickel powder substrate when coated with a polymeric mesh coating,as described above, provides a substrate surface effect whichsubstantially reduces battery cell shorting and provides extendedrechargeable battery cell life cycling performance by substantiallyreducing the number of metallic fiber ends extending from the surface ofthe electrode when the electrode is chemically loaded and rolled orspirally-wound to complete the cell assembly.

The synthetic mesh, netting or web fabric 20 is a polymeric fabric whichis preferably selected to provide a porous chemically resistant surfacewhich is compatible with the electrolyte system used in the completedelectrode battery. Although not shown in the drawings, the syntheticmesh or web fabric 20 may be applied to the nickel fiber-nickel powdersubstrate 10 by utilizing a hot melt spray, an aqueous slurry,conventional air and wet layering, steam calendering of preformedfabrics and hot calender lamination of the preformed fabric.

A further embodiment of the present invention is shown schematically inFIGS. 5, 6 and 7 which generally illustrate the utilization of a porouscovering layer means comprised of fine diameter metallic nickel fibers30 which are applied to and bonded to at least one or more of the outersurfaces of the three-dimensional sintered nickel fiber-nickel powdersubstrate 10. As shown and illustrated in FIG. 5, the process includesthe uncoiling of the sintered nickel fiber-nickel powder substrate 10from the take-up reel 19 and directing this substrate to receive finediameter nickel fibers 30 which are applied by an upper surface coatingapparatus 31 including a spray coating apparatus 32 and includingreservoir 33. The fine diameter nickel fibers 30 may have a range ofdiameters of between 5-18 microns and preferably will have a nominaldiameter of approximately 10 microns. The diameter of the fine nickelcovering fibers is to be compared with the nickel fiber contained in thenickel powder substrate 10 wherein the nominal diameter of such nickelfibers is approximately 25 microns. The application of the surfacecoating of one or more layers of fine diameter nickel fibers 30 providesa multiple layered fiber cover or surface 30A on the nickel fiber-nickelpowder substrate 10 which is then passed through a drying oven 34 andthen passed through sintering oven 35 which bonds the multiple layeredsurface of fine diameter nickel fibers onto the larger diameter nickelfiber-nickel powder substrate 10 to provide a coated substrate 28A'having a multi-layered fine fiber surface 30A on the upper surface ofthe three-dimensional electrode substrate prior to the loading of theactive chemical by the electrode manufacture. In the embodiment of theprocess illustrated in FIG. 5, a multi-layered fiber cover or surface isapplied both to the upper and the lower surfaces of the substrate 10. Tothis end, the upper surface coated substrate 28A' provided at the outputof sintering oven 35 is unloaded to a suitable web inversion apparatus36, which inverts the substrate 28A' top to bottom, and passes theinverted substrate 28A' "lower surface-up" to a lower surface coatingapparatus 31' which includes a reservoir 33' drying oven 34' sinteringoven 35', calendering rollers 37 and sintering oven 38 which provide amultiple layered fiber cover or surface 30A and the lower surface of thenickel fiber-nickel powder substrate 10, thereby providing the coatedsubstrate 28A which is wound on a take-up reel 19. For applicationswhere only the upper surface of the substrate 10 is coated with finediameter nickel fibers 30, the coated substrate 28A' provided at theoutput of the sintering oven 35 of the upper surface coating apparatus31 can be directed to calender rolls 37, sintering oven 38 and wound ona take-up reel.

For example, it has been found that a water based slurry containing 25percent by weight nominal 10 micron diameter nickel fibers was sprayedthrough the coating apparatus 32 onto the substrate 10, i.e., both onthe top surface of the substrate and on the lower surface of the topcoated substrate, the porous layer of fine diameter nickel fibersyielded a surface coating of containing 25 grams per meter² on eachsurface. The weight percent of finer diameter nickel fiber in thesurface coating may range between 10 to 60 grams per meter².

As shown in FIG. 6, a schematic top view of the coated substrate 28Ashows the overlying upper and lower surfaces 30A containing finediameter nickel fibers 30 overlying the inner portion of the nickelfiber-nickel powder substrate 10 containing the larger diameter longnickel fibers 12.

Also, FIG. 7 is a cross sectional view taken through lines 7--7 of FIG.6, showing the deposit or coating 30A of multiple layers of fine fibers30 bonded to the surface of the nickel fiber-nickel powder substrate 10.Again, the resultant multi-layered battery electrode matrix provides anelectrode structure which possesses increase loading and retention ofthe electrode active material. Additionally, the multiple layers 30A offine diameter fibers 30 provides a substrate surface affect whichsubstantially reduces battery cell shorting and provides extendedrechargeable battery cell life cycling by reducing the number ofmetallic fiber ends which would extend from the surface of the electrodeafter the electrode is chemically loaded and then rolled orspirally-wound to complete the cell assembly. The layering of the finediameter nickel fibers 30 onto the nickel fiber-nickel powder substrate10, together with the subsequent calendering and sintering operationforms the electrode substrate into a non-woven metallic fabric of aspecified density, thickness, porosity and weight, as desired by theelectrode manufacturer. The layered metallic surface coating increasesthe conductivity and lowers the resistivity of the resultant loaded cellelectrode and provides that about 2-5 percent increase in electricalcapacity of resultant rechargeable batteries utilizing the multiplelayer of fine fibers bonded to the three-dimensinal nickel fiber-nickelpowder substrate.

In still a further embodiment of the present invention illustrated inFIGS. 8 and 9, a flexible fine mesh metal screen 40 may be directlybonded to at least one surface of the nickel fiber-nickel powdersubstrate 10 to form an electrode structure 28B. The metal screen 40 ispreferably of approximately 40 mesh in size and may be composed ofnickel, nickel coated steel or stainless steel. The screen is bonded toat least one surface of the nickel fiber-nickel powder substrate bybrazing, or spot welding or sintering to provide a substratesandwich-like structure that may be chemically loaded and spirally-woundto complete the electrode assembly. The screen 40 prevents andsubstantially reduces the number of metallic fiber ends extending fromthe surface of the electrode after the electrode is chemically loadedand wound to complete the electrode cell assembly.

It is also within the scope of the prevent invention that the porouscovering layer bonded to at least one surface of the three-dimensionalelectrode provides a loaded cell electrode structure that possessesincreased conductivity and lowered resistivity over non-coatedthree-dimensional electrodes. This permits the electrode material of thepresent invention to be used in spiral-wound electrode cells as well asbe used in planar or plaque cells which may be stacked in the completedcell assembly. Although such planar or button cells may be configured orstacked in a final cell assembly as a non-planar arc, in this sense,they are considered substantially planar for purposes of thisdisclosure.

                  TABLE I                                                         ______________________________________                                                 Prior Art                                                                              Fine Ni Fiber                                                                             Resin Bonded                                             NI Fiber Bonded to Ni                                                                              to Ni Fiber                                              Substrate                                                                              Fiber Substrate                                                                           Substrate                                       ______________________________________                                        LOADING    1      gm/in.sup.2                                                                           1.1   gm/in.sup.2                                                                         1.1  gm/in.sup.2                        Paste      1550   gm/m.sup.2                                                                            1700  gm/m.sup.2                                                                          1700 gm/m.sup.2                         LOADING    1240   gm/m.sup.2                                                                            1360  gm/m.sup.2                                                                          1360 gm/m.sup.2                         Ni(OH).sub.2                                                                  Utilization                                                                              80%            83%         80%                                     of Ni(OH).sub.2                                                               Useful     0.8    gm/in.sup.2                                                                           0.91  gm/in.sup.2                                                                         0.88 gm/in.sup.2                        Ni(OH).sub.2                                                                  Amp/Hour/m.sup.2                                                                         286            326         314                                     Capacity                                                                      ______________________________________                                    

As shown in Table I, the resin mesh bonded to the surfaces of athree-dimensional sintered nickel fiber-nickel powder substrate yieldsan amp per hour capacity of 314. The three-dimensional substratematerial when coated with a multiple layer of fine nickel fiberspossesses amp per hour capacity of 326. In comparison, the amp per hourcapacity of a sintered nickel fiber-nickel powder substrate as anelectrode material possesses an amp per hour capacity of 286. Thisshould be compared to an amp per hour capacity of 210 for a planarelectrode which is comprised of nickel powder sintered onto a metal meshstructure.

Additionally, when compared with a nickel-cadmium AA cell whichpossesses 550 milliamps per hour output, the output of the sinterednickel fiber-nickel powder substrate is 700, the output of theresin-mesh coated nickel fiber-nickel powder substrate is 770, and theoutput of the multiple-layered fine fiber bonded to thethree-dimensional nickel fiber-nickel powder substrate is 790. Also,when a similar comparison is made to a nickel metal hydrid AA batteryhaving an output of 1,000 milliamps per hour, the three-dimensionalnickel fiber-nickel powder substrate possesses an output of 1272,milliamps, the resin bonded three-dimensional substrate possesses anoutput of 1400, milliamps, and the multi-layered fiber bondedthree-dimensional nickel fiber-nickel powder substrate possesses anoutput of 1436. Accordingly, a porous covering layer means positioned onat least one surface of the three-dimensional nickel fiber-nickel powdersubstrate provides for significant improved output as well as forsignificant improved loading of the active chemical material into thesubstrate.

Additionally, such treated and layered structures made in accordancewith the present invention result in a manufacturing loss of less thanone half of one percent due to shorting problems. This is compared to amanufacturing loss of approximately 10 percent due to shorting when thethree-dimensional nickel fiber-nickel powder substrate in accordancewith the prior art is spirally-wound into an electrode cell. Thus,because the novel structures in accordance with the present inventionretain more active material by utilizing and retaining more of theactive material or nickel hydroxide there exist approximately a 10-12percent improvement in the utilization of the active material in theresultant electrode cell assembly, thereby substantially increasing theoutput of the electrode cell.

We claim:
 1. A three-dimensional substrate material for use inconstructing battery electrodes comprising:a sintered matrix materialselected from the group of elements consisting of reticulated metalfoams, conductive fibers and metal powder compacts, said matrix materialhaving at least one flexible bonded open surface structure, and aflexible open surface matrix retaining means bonded to at least onesurface of said sintered matrix material, with said retaining meansstructurally arranged to permit loading of active chemical materialthrough said retaining means into said sintered matrix material and toretain said sintered matrix material substantially within the formedsurface of said at least one surface of said matrix material duringsubsequent spiral-winding of the sintered matrix material.
 2. Thethree-dimensional substrate material in accordance with claim 1 whereinsaid retaining means is a polymeric mesh material.
 3. Thethree-dimensional substrate material in accordance with claim 2 whereinsaid polymeric mesh material is selected from the group consisting ofpolyesters, polyolefins and polyamides.
 4. The three-dimensionalsubstrate material in accordance with claim 2 wherein said polymericmesh material is nylon.
 5. The three-dimensional substrate material inaccordance with claim 1 wherein said retaining means is comprised ofnickel fibers having a diameter between about 5-18 microns.
 6. Thethree-dimensional substrate material in accordance claim 5 wherein saidnickel fibers have a diameter of about 10 microns.
 7. Thethree-dimensional substrate material in accordance with claim 1 whereinsaid sintered matrix material is comprised of conductive metal fibers.8. The three-dimensional substrate material in accordance with claim 7wherein said conductive metal fibers are comprised of 70-90 weightpercent nickel fibers and 30-10 weight percent nickel powder.
 9. Thethree-dimensional substrate material in accordance claim 7 wherein saidconductive metal fibers are comprised of 80 weight percent nickel fiberand 20 weight percent nickel powder.
 10. The three-dimensional substratematerial in accordance claim 8 wherein said retaining means is apolymeric mesh material.
 11. The three-dimensional substrate material inaccordance with claim 10 wherein said polymeric mesh material isselected from the group consisting of polyesters, polyolefins andpolyamides.
 12. The three-dimensional substrate material in accordancewith claim 10 wherein said polymeric mesh material is nylon.
 13. Thethree-dimensional substrate material in accordance with claim 8 whereinsaid retaining means is comprised of nickel fibers having a diameterbetween about 5-18 microns.
 14. The three-dimensional substrate materialin accordance claim 13 wherein said porous covering layer means bondedto at least one surface is comprised of a coating weight of nickelfibers of between 10-60 grams per meter².
 15. The three-dimensionalsubstrate material in accordance with claim 14 wherein said coatingweight of nickel fibers is about 25 grams per meter².
 16. Thethree-dimensional substrate material in accordance with claim 1 whereinsaid retaining means is a flexible metal screen.
 17. Thethree-dimensional substrate material in accordance with claim 16 whereinsaid flexible metal screen is a 40 mesh screen.
 18. Thethree-dimensional substrate material in accordance with claim 16 whereinsaid flexible metal screen is selected from a group consisting ofnickel, nickel coated steel and stainless steel.
 19. A three-dimensionalsubstrate material for use in constructing substantially planar batteryelectrodes comprising:a sintered matrix material selected from the groupof elements consisting of reticulated metal foams, conductive fibers andmetal powder compacts, said matrix material having at least one flexiblybonded open surface structure, and an open surface matrix retainingmeans bonded to at least one surface of said sintered matrix material,with said retaining means structurally arranged to permit loading ofactive chemical material through said retaining means into said sinteredmatrix material and to retain said sintered matrix materialsubstantially within the planar surface of said at least one surface ofsaid sintered matrix material when said sintered matrix material plaquesare assembled into the substantially planar battery electrode cell. 20.The three-dimensional substrate material in accordance with claim 19wherein said retaining means is a polymeric mesh material.
 21. Thethree-dimensional substrate material in accordance with claim 20 whereinsaid polymeric mesh material is selected from the group consisting ofpolyesters, polyolefins and polyamides.
 22. The three-dimensionalsubstrate material in accordance with claim 20 wherein said polymericmesh material is nylon.
 23. The three-dimensional substrate material inaccordance with claim 19 wherein said retaining means is comprised ofnickel fibers having a diameter between about 5-18 microns.
 24. Thethree-dimensional substrate material in accordance claim 23 wherein saidnickel fibers have a diameter of about 10 microns.
 25. Thethree-dimensional substrate material in accordance with claim 19 whereinsaid sintered matrix material is comprised of conductive metal fibers.26. The three-dimensional substrate material in accordance with claim 25wherein said conductive metal fibers are comprised of 70-90 weightpercent nickel fibers and 30-10 weight percent nickel powder.
 27. Thethree-dimensional substrate material in accordance with claim 25 whereinsaid conductive metal fibers are comprised of 80 weight percent nickelfiber and 20 weight percent nickel powder.
 28. The three-dimensionalsubstrate material in accordance claim 26 wherein said retaining meansis a polymeric mesh material.
 29. The three-dimensional substratematerial in accordance with claim 28 wherein said polymeric meshmaterial is selected from the group of polyesters, polyolefins andpolyamides.
 30. The three-dimensional substrate material in accordancewith claim 28 wherein said polymeric mesh material is nylon.
 31. Thethree-dimensional substrate material in accordance with claim 26 whereinsaid retaining means is comprised of nickel fibers having a diameterbetween about 5-18 microns.
 32. The three-dimensional substrate materialin accordance claim 31 wherein said retaining means bonded to at leastone surface is comprised of coating weight of nickel fibers of between10-60 grams per meter².
 33. The three-dimensional substrate material inaccordance with claim 32 wherein said coating weight of nickel fibers isabout 25 grams per meter².
 34. The three-dimensional substrate materialin accordance with claim 19 wherein said retaining means is a flexiblemetal screen.
 35. The three-dimensional substrate material in accordancewith claim 34 wherein said flexible metal screen is a 40 mesh screen.36. The three-dimensional substrate material in accordance with claim 34wherein said flexible metal screen is selected from a group consistingof nickel, nickel coated steel and stainless steel.